Generally, in an optical recording and reproduction of information in which an optical beam is used, it is necessary to focus an optical beam on a signal recording surface of a recording medium, such as an optical disc, using a so-called objective lens. At this time, in particular, if a surface of the objective lens is contaminated due to the fact that a film or the like composed of organic matter or the like is formed thereon, the focusing performance is reduced, or the transmittance itself of optical beam or the like is reduced, because of the reflection or the like based on the film or the like. As a result, for example, the reduction of S/N ratio or the like occurs in recording and reproduction. In many cases, a film composed of organic matter or the like is formed due to the fact that, for example, a finger of a person touches a surface of an objective lens exposed to a recording medium, or dust in air is deposited on the surface.
Patent Document No. 1 mentioned below discloses that a cleaning film of photo-catalyst or the like activated by radiation of an optical beam for recording and reproduction is formed on a surface of an objective lens, and thereby, the recording and reproduction by use of the optical beam, and the cleaning of objective lens by use of the cleaning film are carried out concurrently.
Further, Patent Document No. 2 mentioned below discloses that a radiation unit for radiating an optical beam for cleaning, and a radiation unit for radiating an optical beam for recording and reproduction are provided separately, and the optical beam for cleaning is reflected by a recording medium, and radiated on an objective lens, and thereby, the objective lens is cleaned, even in a condition where the recording medium is loaded.
The cleaning of an objective lens by a cleaning film is carried out due to the fact that the cleaning film is activated by the radiation of an optical beam on the cleaning film, and thereby, organic matter or the like attached to a surface thereof is dissolved into carbon dioxide, water (moisture), and the like, and disappears.
On the other hand, in recent years, in addition to a conventional CD (Compact Disc) and a conventional DVD (Digital Versatile Disc), a high-density optical disc in which a recording capacity of information is further increased becomes generalized. Further, a recording and reproduction apparatus, which has compatibility of being capable of recording and reproducing information in and from a plurality of kinds of optical discs by one recording and reproduction apparatus, is also developed.
At this time, while information can be recorded and reproduced with a so-called red laser beam as an optical beam in the case of a CD and a DVD, information is recorded and reproduced with a blue laser beam whose wavelength is shorter than the red laser beam in the case of a high-density optical disc. In a recording and reproduction apparatus mentioned above which has compatibility, generally, an objective lens for a CD/DVD (namely, for a red laser beam), and an objective lens for a high-density optical disc (namely, for a blue laser beam) are provided separately, and by adequately changing these objective lenses, information is recorded and reproduced in and from a CD or a DVD, or a high-density optical disc.    Patent Document No. 1: Japanese Patent Laid-open No. 2003-51134 (for example, FIG. 3)    Patent Document No. 2: International Publication No. 2007/142020 (for example, FIG. 2)